Applied Genetics

Selective breeding is a method where humans control the genetics of other species to achieve desired traits. There are two primary methods: hybridization and inbreeding.

Hybridization combines beneficial traits from different organisms to create a new organism with superior qualities. Inbreeding, conversely, aims to maintain desired traits within a population, as seen with champion racehorses or specific dog breeds.

Hybridization is time-consuming and expensive, requiring many generations to achieve true breeding. Inbreeding increases the risk of homozygous recessive offspring, potentially leading to undesirable traits or defects.

An example demonstrates how inbreeding gradually minimizes an undesirable 'purple' gene over several generations, eventually resulting in a population with only the desired 'blue' trait.

Hybridization involves getting two separate populations to true breed for different desirable traits. Once true breeding, these populations are crossed to create hybrids with combined advantageous traits.

Historical paintings from the 17th century illustrate how watermelons have been selectively bred over hundreds of years to alter their appearance, fruit structure, and seed size, significantly differing from their original state.

A test cross is used to determine the genotype of an unknown individual. By crossing the unknown with a known homozygous recessive individual, the phenotypes of the offspring can reveal whether the unknown parent is homozygous or heterozygous.